A survey of RFID readers anticollision protocols

International audienceWhile RFID technology is gaining increased attention from industrial community deploying different RFID-based applications, it still suffers from reading collisions. As such, many proposals were made by the scientific community to try and alleviate that issue using different techniques either centralized or distributed, monochannel or multichannels, TDMA or CSMA. However, the wide range of solutions and their diversity make it hard to have a clear and fair overview of the different works. This paper surveys the most relevant and recent known state-of-the-art anti-collision for RFID protocols. It provides a classification and performance evaluation taking into consideration different criteria as well as a guide to choose the best protocol for given applications depending on their constraints or requirements but also in regard to their deployment environments

Distributed Efficient & Fair Anticollision for RFID Protocol

International audienceRFID technology suffers from a recurring issue: the reader-to-reader collision. Numerous protocols have been proposed to attempt to reduce them, but, remaining reading errors still heavily impact the performances and fairness of dense RFID deployments. This paper introduces a new Distributed Efficient & Fair Anticollision for RFID (DEFAR) protocol. It reduces both monochannel and multichannel collisions as well as interference by a factor of almost 90% in comparison with the best state of the art protocols. The fairness of the medium access among the readers is improved to a 99% level. Such improvements are achieved applying a TDMA-based "server-less" approach and assigning different priorities to readers depending on their behavior over precedent rounds. A distributed reservation phase is organized between readers with at least one winning reader afterwards. Then, multiple reading phases occur within a single frame in order to obtain fast coverage and high throughput. The use of different reader priorities based on reading behaviors of previous frames also contributes to improve both fairness and efficiency. Simulation results show the robustness of the proposed solution in terms of different metrics such collision avoidance, fairness and coverage and in comparison with a centralized literature solution

An MILP-Based Cross-Layer Optimization for a Multi-Reader Arbitration in the UHF RFID System

In RFID systems, the performance of each reader such as interrogation range and tag recognition rate may suffer from interferences from other readers. Since the reader interference can be mitigated by output signal power control, spectral and/or temporal separation among readers, the system performance depends on how to adapt the various reader arbitration metrics such as time, frequency, and output power to the system environment. However, complexity and difficulty of the optimization problem increase with respect to the variety of the arbitration metrics. Thus, most proposals in previous study have been suggested to primarily prevent the reader collision with consideration of one or two arbitration metrics. In this paper, we propose a novel cross-layer optimization design based on the concept of combining time division, frequency division, and power control not only to solve the reader interference problem, but also to achieve the multiple objectives such as minimum interrogation delay, maximum reader utilization, and energy efficiency. Based on the priority of the multiple objectives, our cross-layer design optimizes the system sequentially by means of the mixed-integer linear programming. In spite of the multi-stage optimization, the optimization design is formulated as a concise single mathematical form by properly assigning a weight to each objective. Numerical results demonstrate the effectiveness of the proposed optimization design

How to improve CSMA-based MAC protocol for dense RFID reader-to-reader Networks?

International audienceDue to the dedicated short range communication feature of passive radio frequency identification (RFID) and the closest proximity operation of both tags and readers in a large-scale dynamic RFID system, when nearby readers simultaneously try to communicate with tags located within their interrogation range, serious interference problems may occur. Such interferences may cause signal collisions that lead to the reading throughput barrier and degrade the system performance. Although many efforts have been done to maximize the throughput by proposing protocols such as NFRA or more recently GDRA, which is compliant with the EPCglobal and ETSI EN 302 208 standards. However, the above protocols are based on unrealistic assumptions or require additional components with more control packet and perform worse in terms of collisions and latency, etc. In this paper, we explore the use of some well-known Carrier Sense Multiple Access (CSMA) backoff algorithms to improve the existing CSMA-based reader-to-reader anti-collision protocol in dense RFID networks. Moreover, the proposals are compliant with the existing standards. We conduct extensive simulations and compare their performance with the well-known state-of-the-art protocols to show their performance under various criteria. We find that the proposals improvement are highly suitable for maximizing the throughput, efficiency and for minimizing both the collisions and coverage latency in dense RFID Systems

Data Gathering Solutions for Dense RFID Deployments

International audienceThe advent of RFID (Radio Frequency Identification) has allowed the development of numerous applications. Indeed, solutions such as tracking of goods in large areas or sensing in smart cities are now made possible. However, such solutions encounter two main issues, first is inherent to the technology itself which is readers collisions, the second one being the gathering of read data up to a base station, potentially in a multihop fashion. While the first one has been a main research subject in the late years, the next one has not been investigated for the sole purpose of RFID, but rather for wireless adhoc networks. This multihop tag information collection must be done in regards of the application requirements but it should also care for the deployment strategy of readers to take advantage of their relative positions, coverage, reading activity and deployment density to avoid interfering between tag reading and data forwarding. To the best of our knowledge, the issue for a joint scheduling between tag reading and forwarding has never been investigated so far in the literature, although important.In this paper, we propose two new distributed, crosslayer solutions meant for the reduction of collisions and better efficiency of the RFID system but also serve as a routing solution towards a base station. Simulations show high levels of throughput while not lowering on the fairness on medium access staying above 85% in the highest deployment density with up to 500 readers, also providing a 90% data rate

Reliable Communication in Wireless Networks

Wireless communication systems are increasingly being used in industries and infrastructures since they offer significant advantages such as cost effectiveness and scalability with respect to wired communication system. However, the broadcast feature and the unreliable links in the wireless communication system may cause more communication collisions and redundant transmissions. Consequently, guaranteeing reliable and efficient transmission in wireless communication systems has become a big challenging issue. In particular, analysis and evaluation of reliable transmission protocols in wireless sensor networks (WSNs) and radio frequency identification system (RFID) are strongly required. This thesis proposes to model, analyze and evaluate self-configuration algorithms in wireless communication systems. The objective is to propose innovative solutions for communication protocols in WSNs and RFID systems, aiming at optimizing the performance of the algorithms in terms of throughput, reliability and power consumption. The first activity focuses on communication protocols in WSNs, which have been investigated, evaluated and optimized, in order to ensure fast and reliable data transmission between sensor nodes. The second research topic addresses the interference problem in RFID systems. The target is to evaluate and develop precise models for accurately describing the interference among readers. Based on these models, new solutions for reducing collision in RFID systems have been investigated

Advances in analytical models and applications for RFID, WSN and AmI systems

Experimentos llevados a cabo con el equipo de división de honor UCAM Volleyball Murcia.[SPA] Internet de las cosas (IoT) integra distintos elementos que actúan tanto como fuentes, como sumideros de información, a diferencia de la percepción que se ha tenido hasta ahora de Internet, centrado en las personas. Los avances en IoT engloban un amplio número de áreas y tecnologías, desde la adquisición de información hasta el desarrollo de nuevos protocolos y aplicaciones. Un concepto clave que subyace en el concepto de IoT, es el procesamiento de forma inteligente y autónoma de los flujos de información que se dispone. En este trabajo, estudiamos tres aspectos diferentes de IoT. En primer lugar, nos centraremos en la infraestructura de obtención de datos. Entre las diferentes tecnologías de obtención de datos disponibles en los sistemas IoT, la Identificación por Radio Frecuencia (RFID) es considerada como una de las tecnologías predominantes. RFID es la tecnología detrás de aplicaciones tales como control de acceso, seguimiento y rastreo de contenedores, gestión de archivos, clasificación de equipaje o localización de equipos. Con el auge de la tecnología RFID, muchas instalaciones empiezan a requerir la presencia de múltiples lectores RFID que operan próximos entre sí y conjuntamente. A estos escenarios se les conoce como dense reader environments (DREs). La coexistencia de varios lectores operando simultáneamente puede causar graves problemas de interferencias en el proceso de identificación. Uno de los aspectos claves a resolver en los RFID DREs consiste en lograr la coordinación entre los lectores. Estos problemas de coordinación son tratados en detalle en esta tesis doctoral. Además, dentro del área de obtención de datos relativa a IoT, las Redes de Sensores Inalámbricas (WSNs) desempeñan un papel fundamental. Durante la última década, las WSNs han sido estudiadas ampliamente de forma teórica, y la mayoría de problemas relacionados con la comunicación en este tipo de redes se han conseguido resolver de forma favorable. Sin embargo, con la implementación de WSNs en proyectos reales, han surgido nuevos problemas, siendo uno de ellos el desarrollo de estrategias realistas para desplegar las WSN. En este trabajo se estudian diferentes métodos que resuelven este problema, centrándonos en distintos criterios de optimización, y analizando las diferentes ventajas e inconvenientes que se producen al buscar una solución equilibrada. Por último, la Inteligencia Ambiental (AmI) forma parte del desarrollo de aplicaciones inteligentes en IoT. Hasta ahora, han sido las personas quienes han tenido que adaptarse al entorno, en cambio, AmI persigue crear entornos de obtención de datos capaces de anticipar y apoyar las acciones de las personas. AmI se está introduciendo progresivamente en diversos entornos reales tales como el sector de la educación y la salud, en viviendas, etc. En esta tesis se introduce un sistema AmI orientado al deporte que busca mejorar el entrenamiento de los atletas, siendo el objetivo prioritario el desarrollo de un asistente capaz de proporcionar órdenes de entrenamiento, basadas tanto en el entorno como en el rendimiento de los atletas. [ENG] Internet of Things (IoT) is being built upon many different elements acting as sources and sinks of information, rather than the previous human-centric Internet conception. Developments in IoT include a vast set of fields ranging from data sensing, to development of new protocols and applications. Indeed, a key concept underlying in the conception of IoT is the smart and autonomous processing of the new huge data flows available. In this work, we aim to study three different aspects within IoT. First, we will focus on the sensing infrastructure. Among the different kind of sensing technologies available to IoT systems, Radio Frequency Identification (RFID) is widely considered one of the leading technologies. RFID is the enabling technology behind applications such as access control, tracking and tracing of containers, file management, baggage sorting or equipment location. With the grow up of RFID, many facilities require multiple RFID readers usually operating close to each other. These are known as Dense Reader Environments (DREs). The co-existence of several readers operating concurrently is known to cause severe interferences on the identification process. One of the key aspects to solve in RFID DREs is achieving proper coordination among readers. This is the focus of the first part of this doctoral thesis. Unlike previous works based on heuristics, we address this problem through an optimization-based approach. The goal is identifying the maximum mean number of tags while network constraints are met. To be able to formulate these optimization problems, we have obtained analytically the mean number of identifications in a bounded -discrete or continuous- time period, an additional novel contribution of our work. Results show that our approach is overwhelmingly better than previous known methods. Along sensing technologies of IoT, Wireless Sensor Networks (WSNs) plays a fundamental role. WSNs have been largely and theoretically studied in the past decade, and many of their initial problems related to communication aspects have been successfully solved. However, with the adoption of WSNs in real-life projects, new issues have arisen, being one of them the development of realistic strategies to deploy WSNs. We have studied different ways of solving this aspect by focusing on different optimality criteria and evaluating the different trade-offs that occur when a balanced solution must be selected. On the one hand, deterministic placements subject to conflicting goals have been addressed. Results can be obtained in the form of Pareto-frontiers, allowing proper solution selection. On the other hand, a number of situations correspond to deployments were the nodes¿ position is inherently random. We have analyzed these situations leading first to a theoretical model, which later has been particularized to a Moon WSN survey. Our work is the first considering a full model with realistic properties such as 3D topography, propellant consumptions or network lifetime and mass limitations. Furthermore, development of smart applications within IoT is the focus of the Ambient Intelligence (AmI) field. Rather than having people adapting to the surrounding environment, AmI pursues the development of sensitive environments able to anticipate support in people¿s actions. AmI is progressively being introduced in many real-life environments like education, homes, health and so forth. In this thesis we develop a sport-oriented AmI system designed to improve athletes training. The goal is developing an assistant able to provide real-time training orders based on both environment and athletes¿ biometry, which is aimed to control the aerobic and the technical-tactical training. Validation experiments with the honor league UCAM Volleyball Murcia team have shown the suitability of this approach.[ENG] Internet of Things (IoT) is being built upon many different elements acting as sources and sinks of information, rather than the previous human-centric Internet conception. Developments in IoT include a vast set of fields ranging from data sensing, to development of new protocols and applications. Indeed, a key concept underlying in the conception of IoT is the smart and autonomous processing of the new huge data flows available. In this work, we aim to study three different aspects within IoT. First, we will focus on the sensing infrastructure. Among the different kind of sensing technologies available to IoT systems, Radio Frequency Identification (RFID) is widely considered one of the leading technologies. RFID is the enabling technology behind applications such as access control, tracking and tracing of containers, file management, baggage sorting or equipment location. With the grow up of RFID, many facilities require multiple RFID readers usually operating close to each other. These are known as Dense Reader Environments (DREs). The co-existence of several readers operating concurrently is known to cause severe interferences on the identification process. One of the key aspects to solve in RFID DREs is achieving proper coordination among readers. This is the focus of the first part of this doctoral thesis. Unlike previous works based on heuristics, we address this problem through an optimization-based approach. The goal is identifying the maximum mean number of tags while network constraints are met. To be able to formulate these optimization problems, we have obtained analytically the mean number of identifications in a bounded -discrete or continuous- time period, an additional novel contribution of our work. Results show that our approach is overwhelmingly better than previous known methods. Along sensing technologies of IoT, Wireless Sensor Networks (WSNs) plays a fundamental role. WSNs have been largely and theoretically studied in the past decade, and many of their initial problems related to communication aspects have been successfully solved. However, with the adoption of WSNs in real-life projects, new issues have arisen, being one of them the development of realistic strategies to deploy WSNs. We have studied different ways of solving this aspect by focusing on different optimality criteria and evaluating the different trade-offs that occur when a balanced solution must be selected. On the one hand, deterministic placements subject to conflicting goals have been addressed. Results can be obtained in the form of Pareto-frontiers, allowing proper solution selection. On the other hand, a number of situations correspond to deployments were the nodes¿ position is inherently random. We have analyzed these situations leading first to a theoretical model, which later has been particularized to a Moon WSN survey. Our work is the first considering a full model with realistic properties such as 3D topography, propellant consumptions or network lifetime and mass limitations. Furthermore, development of smart applications within IoT is the focus of the Ambient Intelligence (AmI) field. Rather than having people adapting to the surrounding environment, AmI pursues the development of sensitive environments able to anticipate support in people¿s actions. AmI is progressively being introduced in many real-life environments like education, homes, health and so forth. In this thesis we develop a sport-oriented AmI system designed to improve athletes training. The goal is developing an assistant able to provide real-time training orders based on both environment and athletes¿ biometry, which is aimed to control the aerobic and the technical-tactical training. Validation experiments with the honor league UCAM Volleyball Murcia team have shown the suitability of this approach.Universidad Politécnica de CartagenaPrograma de doctorado en Tecnología de la Información y de las Comunicacione

Towards machine learning enabled future-generation wireless network optimization

We anticipate that there will be an enormous amount of wireless devices connected to the Internet through the future-generation wireless networks. Those wireless devices vary from self-driving vehicles to smart wearable devices and intelligent house- hold electrical appliances. Under such circumstances, the network resource optimization faces the challenge of the requirement of both flexibility and performance. Current wireless communication still relies on one-size-fits-all optimization algorithms, which require meticulous design and elaborate maintenance, thus not flexible and cannot meet the growing requirements well. The future-generation wireless networks should be “smarter”, which means that the artificial intelligence-driven software-level design will play a more significant role in network optimization. In this thesis, we present three different ways of leveraging artificial intelligence (AI) and machine learning (ML) to design network optimization algorithms for three wireless Internet of things network optimization problems. Our ML-based approaches cover the use of multi-layer feed-forward artificial neural network and the graph convolutional network as the core of our AI decision-makers. The learning methods are supervised learning (for static decision-making) and reinforcement learning (for dynamic decision-making). We demonstrate the viability of applying ML in future- generation wireless network optimizations through extensive simulations. We summarize our discovery on the advantage of using ML in wireless network optimizations as the following three aspects: 1. Enabling the distributed decision-making to achieve the performance that near a centralized solution, without the requirement of multi-hop information; 2. Tackling with dynamic optimization through distributed self-learning decision- making agents, instead of designing a sophisticated optimization algorithm; 3. Reducing the time used in optimizing the solution of a combinatorial optimization problem. We envision that in the foreseeable future, AI and ML could help network service designers and operators to improve the network quality of experience swiftly and less expensively

Realistic chipless RFID: protocol, encoding and system latency

Chiplose Identifikation über Funkfrequenzen, RFID (engl., Radio Frequency IDentification) ist eine vielversprechende Technology, der man die Fähigkeit zuschreibt, in naher Zukunft den optischen Barcode zu ersetzen. Letztgenannter hat Einschränkungen durch i) RFID Tags sind bei nicht vorhandener Sichtverbindung (engl. Non-Line-Of-Sight, NLOS) auch nicht lesbar; ii) das Scannen der Barcodes benötigt in den meisten Fällen manuelles Eingreifen; iii) es ist unmöglich mehrere Barcodes gleichzeitig auszulesen; iv) und als Folge davon entsprechende Verzögerungen beim Auslesen größerer Mengen von Barcodes, da alle einzeln gescannt werden müssen. Die Beiträge der vorliegenden Dissertation konzentrieren sich auf drei Schwerpunkte von frequenzcodierten (engl. frequency coded, FC) chiplosen RFID Systemen. Der erste Schwerpunkt ist die gleichzeitige Identifikation von mehreren RFID Tags und kümmert sich um den Fall, dass sich mehrere RFID Tags in der Lesezone des RFID Lesegerätes befinden. Der zweite Aspekt betrifft die Verzögerung des Systems, die Zeit, das Lesegerät zum Identifizieren der RFID Tags benötigt. Und drittens die Coding Kapazität des Systems, sie ist verantwortlich für die zu erreichende Bittiefe des RFID Systems. Ein real umsetzbares RFID System erfordert Lösungen in allen drei Aspekten. Da chiplose RFID Tags keine integrierten Schaltungen (ICs) und somit auch keine Speicherbausteine besitzen, ist die Anzahl der auf dem RFID Tag speicherbaren Bits begrenzt. Und als Folge davon sind die Standards und Protokolle, die für die herkömmlichen chipbehafteten RFID Systeme entwickelt worden, nicht auf chiplose RFID Systeme übertragbar. Das wesentliche Ziel des ersten Beitrages ist die Einführung eines neuen Multi-Tag Antikollisionsprotokolls, das auf der Modulation der Notchposition (engl. Notch Position Modulation, NPM) und Tabellen (engl. Look-Up-Table, LUT) zur Bestimmung der Netzwerk- und MAC- Layer des chiplosen RFID Systems basiert. Die erste Generation der vorgeschlagenen Protokolls (Gen-1) baut auf einer Zweiteilung des zur Verfügung stehenden Spektrums auf. Im unteren Frequenzbereich, als Präambel Bandbreite bezeichnet, wird jedem RFID Tag seine individuelle Frequenzverschiebung übermittelt und im zweiten Bereich, der sogenannten Frame Bandbreite, ist die Identifikationsnummer (ID) des RFID Tags hinterlegt. Mit dieser Anordnung lässt sich jegliche Interferenz zwischen den verschiedenen RFID Tags unterbinden, da sich die Antworten der RFID Tags nicht gegenseitig überlagern. Die zweite Generation dieses Protokolls bringt eine Verbesserung sowohl bei der Coding Kapazität als auch bei der Nutzung des zur Verfügung stehenden Frequenzspektrums. Dies wird dadurch erreicht, dass die ID des RFID in einer Tabelle im Lesegerät gespeichert wird. Die individuelle Frequenzverschiebung dient dabei als Adresse für die gespeicherten IDs. Dieser Schritt vereinfacht die Komplexität der Struktur des RFID Tags signifikant, während gleichzeitig die Erkennungswahrscheinlichkeit erhöht wird. Des Weiteren werden die Key Performance Indikatoren untersucht um die Leistungsfähigkeit der Protokolle zu beweisen. Beide Protokollversionen werden modelliert und in einer Umgebung mit 10 chiplosen RFID Tags simuliert, um die Randbedingungen für die Entwicklung der RFID Tags und des RFID Lesegerätes zu ermitteln. Außerdem wird eine neuartige Testumgebung für ein MultiTag Ultra Breitband (engl. ultra wideband UWB) RFID System unter realen Testbedingungen basierend auf einem Software Defined Radio (SDR) Ansatz entwickelt. In dieser Testumgebung werden sowohl die gesendeten Signal als auch Detektierungstechniken, Leerraum Kalibrierung zur Reduzierung der Streustrahlung und die Identifikationsprotokolle untersucht. Als zweiter Schwerpunkt dieser Arbeit werden neue Techniken zur Reduzierung der Systemlaufzeit (engl. System Latency) eingeführt. Das Ziel dabei ist, die Zeit, die das RFID Lesegerät zum Erkennen aller in Lesereichweite befindlichen chiplosen FC RFID Tags braucht, zu verkürzen. Der Großteil der Systemlaufzeit wird durch das gewählte Frequenzscanverfahren, durch die Anzahl der Mittelungen zur Eliminierung der umgebenden Streustrahlung und durch die Dauer eines Frequenzsprungs bestimmt. In dieser werden dazu ein adaptives Frequenzsprungverfahren (engl. adaptive frequency hopping, AFH) sowie ein Verfahren Mittels adaptiver gleitender Fensterung (engl. adaptive sliding window, ASW) eingeführt. Das ASW Verfahren ist dabei im Hinblick auf die Identifizierung der RFID Tags nach dem Gen-1 Protokoll entwickelt, da es ein gleitendes Fenster zur Detektierung der Notches mit einer variablen Breite zum Auslesen der ID erfordert. Im Gegensatz dazu wird das Auffinden der im Gen-2 Protokoll verwendeten Notchpattern durch das AFH Verfahren verbessert. Dies wird über variable Frequenzsprünge, die auf die jeweiligen Notchpattern optimiert werden, erreicht. Beide Verfahren haben sich als effektiv sowohl im Hinblick auf die Systemlaufzeit als auch auf die Genauigkeit erwiesen. Das ASW und das AFH Verfahren wurden dazu in der oben erwähnten Testumgebung implementiert und mit dem klassischen Frequenzsprungverfahren, feste feingraduierte Frequenzschritte, verglichen. Die Experimente haben gezeigt, dass das vorgeschlagene AFH Verfahren in Kombination mit ASW zu einer beachtlichen Reduzierung der Systemlaufzeit von 58% führen. Das Ziel des dritten Schwerpunkts dieser Arbeit ist die Einführung einer neuartigen Technik zur Erhöhung der Informationsdichte (engl. Coding capacity) in einem chiplosen FC RFID Systems. Die hierfür vorgeschlagene Modulation der Notchbreite (engl. notch width modulation, NWM) ermöglicht die Kodierung von 4 Bits (16 Zuständen) pro Resonator in dem die Notchbreite und die dazugehörige Frequenzlage ausgenutzt werden. Für jeden Notch werden 150MHz Bandbreite reserviert, innerhalb derer das Codebit durch eine bestimmte Bandbreiten an unterschiedlichen Frequenzen bestimmt wird Cj ( fk,Bl). Das bedeutet, bei einer Arbeitsfrequenz im Bereich von 2–5 GHz können so 80 Bits realisiert werden. Des Weiteren wurde eine smarte Singulärwertzerlegung (engl. smart singular value decomposition, SSVD) Technik entwickelt, um die Notchbreite zu ermitteln und eine geringe Fehlerwahrscheinlichkeit zu garantieren. Die Nutzung von Blockcodes zur Behebung von Fehlern wurde untersucht, um den größtmöglichen Nutzen aus der so gewonnene Bittiefe zu erzielen. Als Folge konnte eine große Bittiefe mit einer hohen Lesegenauigkeit bei vereinfachtem Aufbau des Lesegeräts erzielt werden. Außerdem wurde eine neuartige RFID Tag Struktur entworfen, die bei einer Größe von 4× 5 cm2 eine Codedichte von 4 Bits/cm2 erreicht. Verschiedene RFID Tag Konfigurationen wurden erstellt und das neu eingeführte Codierungsverfahren mit Hilfe von elektromagnetischen (EM) Simulation und der bereits erwähnten Testplattform überprüft. Die erzielten Ergebnisse ermöglichen ein widerstandsfähiges RFID System in einer realen Umgebung. Alle vorgeschlagenen Beiträge sind durch analytische Modelle, Simulationen und Messungen auf mögliche Probleme und die Grenzen einer Realisierung unter realistischen Bedingungen geprüft worden.Chipless Radio Frequency IDentification (RFID) is a promising technology predicted to replace the optical barcode in the near future. This is due to several problematic issues i) the barcode cannot read Non-Line-Of-Sight (NLOS) tags; ii) each barcode needs human assistance to be read; iii) it is impossible to identify multiple tags at the same time; and iv) the considerable time delay in case of massive queues because different types of objects need to be serially scanned. The contributions included in this dissertation concentrate on three main aspects of the Frequency Coded (FC) chipless RFID system. The first one is the multi-tag identification, which deals with the existence of multiple tags in the reader’s interrogation region. The second aspect is the system latency that describes the time the reader needs to identify the tags. Finally, there is the coding capacity that is responsible for designing a chipless tag with larger information bits. The aim of these aspects is to realize a chipless RFID system. Since the chipless tags are memoryless as they do not include Integrated Circuits (ICs), the number of bits to be stored in the chipless tag is limited. Consequently, the current RFID standards and protocols designed for the chipped RFID systems are not applicable to the chipless systems. The main objective of the first contribution is to introduce novel multi-tag anti-collision protocols based on Notch Position Modulation (NPM) and Look-Up-Table (LUT) schemes determining the network and MAC layers of the chipless RFID systems. The first generation of the proposed protocol (Gen-1) relies on dividing the spectrum into two parts; the first one is the preamble bandwidth that includes a unique frequency shift for each tag. The second part is the frame bandwidth which represents the tag ID. The tag ID is obtained based on the predefined frequency positions, making use of the unique frequency shift. Consequently, the interference is avoided as there will not be any overlap between the tags’ responses. The second generation of the protocol (Gen-2) introduces an improvement in the spectrum utilization and coding capacity. This is realized by transferring the tag-ID to be stored in a table in the main memory of the reader (look-up-table). The unique shift of each tag represents the address of the tag’s ID. Therefore, the complexity of the tag structure will be significantly reduced with an enhanced probability of detection. Furthermore, the key performance indicators for the chipless RFID system are explored to validate the protocol’s performance. Both protocols are modeled and simulated to identify 10-chipless tags in order to set the regulations of the tag and reader design. Moreover, a novel real-world testbed for a multi-tag Ultra Wideband (UWB) chipless RFID system based on Software Defined Radio (SDR) is introduced. In this testbed, all the signaling schemes related to the transmitted signal, the detection techniques, the empty room calibration for the clutter removal process, and the identification protocols are applied. The aim of the second aspect is to introduce novel techniques that reduce the time required by the reader to identify the FC chipless RFID tags existent in the reader’s interrogation region. This time delay is called system latency. The main parameters that significantly affect the overall system latency are the frequency scanning methodology, the number of spectrum scanning iterations for the clutter removal process, and the hop duration. Therefore, the Adaptive Frequency Hopping (AFH) and the Adaptive Sliding Window (ASW) methodologies are proposed to meet the requirements of the FC chipless RFID tags. Regarding the ASW technique, it is suitable to identify the tags using the Gen-1 protocol which utilizes a sliding window (for detecting the notch) with an adaptive size to extract the tag’s-ID. The second adaptive methodology, AFH, can identify the tags with the Gen-2 protocol by using a variable frequency step that fits the corresponding notch patterns. These techniques are proven to be efficient for the chipless RFID systems with regard to latency and accuracy. Likewise, the designed AFH and ASW technique’s performance is compared to the classical Fixed Frequency Hopping (FFH) methodology with a fine frequency step to validate the accuracy of the proposed techniques. A real-world SDR based testbed is designed and the proposed adaptive algorithms as well as the classical FFH methodology are implemented. The experiments show that the proposed AFH combined with the ASW algorithms significantly reduce the system latency by 58%. The goal of the third aspect is to introduce a novel technique that increases the coding capacity of the FC chipless RFID system. The proposed Notch Width Modulation (NWM) scheme encodes 4 bits (16-combinations) per single resonator exploiting the notch bandwidth and its corresponding frequency position. Furthermore, each notch can reserve a window with a bandwidth of 150 MHz and inside this window the notch can obtain a certain bandwidth with a specific resonant frequency constructing the coding pairs Cj ( fk,Bl). Hence, 80-bits could be achieved at the operating frequency 2–5 GHz, preserving the operating frequency bandwidth. Also, a Smart Singular Value Decomposition (SSVD) technique is designed to estimate the notch bandwidth and to ensure a low probability of error. In addition, the utilization of a linear block code as an error correcting code is explored to make the best use of the obtained coding gain. Consequently, a high encoding efficiency and an accurate detection can be achieved in addition to a simplified reader design. Moreover, a novel 4× 5 cm2 tag structure is designed to meet the requirements of the NWM coding technique achieving a coding density of 4 bits/cm2. Different tag configurations are manufactured and validated by measurements using the SDR platform. The introduced coding methodology is conclusively validated using Electromagnetic (EM) simulations and real-world testbed measurements. The considered achievements for the proposed aspects offer a robust chipless RFID system that can be considered in real scenarios. Furthermore, all the proposed contributions are validated using analytical modeling, simulation and measurements in order to list their difficulties and limitations